The present invention relates to food products and to methods for their preparation. More particularly, the present invention is directed towards milled grain products such as wheat flour, to grain intermediate products such as milled bran flours and to their methods of preparation.
The present invention provides improvements in current wheat milling processes for the production of white flour. More particularly, the present invention is directed towards improvements in current wheat milling process to increase the milling extraction rate for flour without a decrease in flour quality.
Generally, the present improved process combines using specific varieties of wheat and isolating a specific millstream and mechanically treating that millstream, removing a portion and adding that portion to the flour.
All wheat varieties generically comprise a major starchy endosperm, a smaller germ or sprouting section of the seed and surrounding bran or husk layer. The endosperm makes up about 82-83% of the wheat kernel and is used in the production of flour. Typically, the bran makes up 14-15%, is removed from the kernel and is used in animal and poultry feed. However, the bran can also be milled along with the endosperm to produce whole-wheat flour. The germ is usually separated from the rest of the kernel because its fat content limits the shelf life of the flour. The bran with or without the germ is sometimes referred to as xe2x80x9cmillfeedxe2x80x9d. Some special purpose whole grain flours include not only the bran but also the germ fraction. The present methods are directed toward the provision of conventional white flour rather than such whole grain flours.
In the United States, wheat is classified according to whether it is hard or soft, white or red, and winter or spring. As a result there are eight possible designations including: hard white spring, hard red spring, hard white winter, hard red winter, soft white spring, soft red spring, soft white winter, and soft red winter.
The hard or soft designation refers to the hardness characteristics of the wheat kernel. Hard wheat is typically used in bread whereas soft wheat is used in cakes and pastries.
The white or red designation refers to the color of the wheat kernel. Currently red wheat is more readily available in the United States than white wheat. Red wheat has a distinctive taste due to tannins in the bran. To minimize the amount of these flavor-bearing tannins, the wheat grain is milled so as to have as small a fraction as possible of the bran containing these tannins. Conversely white wheat has lighter bran color and less bitter bran flavor as compared to red wheat which results in a milling advantage. Naturally white wheat is also increasingly available commercially and being used more and more.
The winter or spring designation refers to the planting and harvesting time of the wheat. Winter wheat is planted in the fall and harvested in the spring, whereas spring wheat is planted in the spring and harvested later in the fall.
Known milling processes can be adjusted or fine-tuned to obtain an increase in the flour yield but at the cost of including some of the bran. The presence of bran may lower the quality and thus value of the flour more than the increase in the value of the increase in yield. That is, the amount of flour obtained during the milling process is limited by contamination of the flour with bran that deteriorates flour quality. For flour made from red wheat, less bran in the flour can be tolerated due to the presence of more color and flavor tannins in the bran. The darker bran typically makes the flour grayish in color, and also imparts bitter flavors to finished products prepared therefrom.
Even though the endosperm fraction is about 83%, in typical white flour milling process, the extraction rate of white patent flour generally runs only about 72-75%. That is, for every hundred pounds of wheat, about 72-75 pounds of flour is obtained. This flour contains about 1-4% dietary fiber from small amounts of the bran. The balance millfeed is very low value comprising bran and germ although containing some of the desirable endosperm. A common use for such millfeed is for animal feed.
In conventional flour milling, the grain is subjected to a series of milling steps that each involve a break system comprised of a pair of break rolls and an associated set of sieves. Coarser fractions that are removed by the sieves are then subsequently milled by the following break system to progressively size reduce the endosperm to produce flour.
Surprisingly, by selecting a hard white wheat as the starting material and by selecting and mechanically treating a particular sub-stream, a size reduced bran flour intermediate can be prepared that can be added to the white flour to increase the yield of total flour while minimizing the amount of undesirable bran in the finished flour. The present invention thus increases the flour extraction rate without decreasing the quality of flour by excessive bran concentration.
While the total increase in flour extraction is deceptively small, (i.e., an increase in extraction from a conventional 72-78% extraction rate to the improved 78%-86% extraction rate), the value of the improvement is disproportionately great due to the commodity nature of the flour milling industry. Wheat flour milling is a high volume low margin commodity business. Thus, any improvement in yield is very valuable as long as the cost of obtaining the increased yield is low. Due to the high fixed and operating costs of flour milling equipment, this seemingly small improvement in extraction can result in the doubling of the profitability of a flour milling plant.
It is a further advantage of the present invention that the improvements can be easily practiced by existing flour milling plants with only modest equipment changes.
These and further objects and advantages of the present invention will become clearer in light of the following detailed description of an illustrative embodiment of this invention described in connection with the drawings.